ELB + ASG

Question 1

What are the benefits of using an ELB?

Answer 1

• health checks enables to forward traffic to only healthy instances
• expose a single point of access to your application
• all your instances will have the same load
• provide SSL termination

Question 2

What are the three types of load balancers available at AWS and its characteristics?

Answer 2

ALB
* Layer 7 load balancer
* It is possible to balance the load based on path, hostname, query string, headers
* great fit for containers, micro services

NLB
* Layer 4 LB
* great for applications that require a very high performance
* one static IP per AZ

GWLB
* useful to analyze incoming traffic
* make traffic go through 3rd party security virtual appliances

Question 3

What if you want fixed IP addresses on your application and features like path or query string routing?

Answer 3

You can create a Network Load Balancer and a ALB as a target group of it.

Question 4

The users of the application are complaining that when they are navigating through your app, it keeps asking for authentication. What can you do?

Answer 4

Implement sticky sessions. This way, the users requests will be sent to the same EC2 instance. However, this can overload some instances.

Question 5

What is cross zone load balancing?

Answer 5

When enabled, EC2 instances located in different AZs will have the load distributed evenly accross all AZs.

Question 6

What is connection draining?

Answer 6

Time to complete in-flight requests while the instance is terminating or deregistering (unhealthy)

Question 7

You have an application that increase the load the same time every day. What kind of scaling policy should be used?

Answer 7

Schedule actions or even predictive scaling, that forecast the load and scale based on it.